VSCode Server on WSL Fails with Download checksum: undefined Error

Bug Reports
1

I’m encountering an issue when trying to launch Cursor in WSL — it fails during the VSCode Server setup with the error:

Download checksum: undefined

I found a similar issue described here:

That post suggests installing the anysphere.remote-wsl extension as a potential workaround. I tried installing it, but unfortunately, it didn’t resolve the problem in my case.

I’d appreciate any help or guidance.

3

Hi! Could you share the output logs for “Remote - WSL” when on the Anysphere extension? It’s likely a network issue with the download, but the logs would confirm. Attaching a screenshot

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4

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same

6

@AuroraMaster – have you already tried restarting your WSL distribution (or restarting your computer?)? Sometimes the network forwarding flakes, in which case a reboot is needed. Otherwise, this could be a firewall issue – Cursor (from Windows) needs to be able to reach a server running within the WSL environment.

7

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In addition, the cursor’s http proxy has also been set to socks5:127.0.0.1:7890
but same after reboot（wsl and windows）

9

To confirm, is the proxy bypass set in system settings? E.g.

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Might need to fully reboot after setting this.

Can you try visiting that link in a web browser (http://127.0.0.1:46449/version – the port might change the next time), and seeing if it loads?

10

Solved
Solution
for WSL Anysphere（cursor） Version need windows .wslconfig Configuration Files
[wsl2] localhostForwarding=true

1 Like
12

Thanks for the response!

I tested again with my WSL project and containers running inside Docker on WSL. Initially, launching them in Cursor didn’t work for several minutes. However, after leaving it alone for about 10 minutes, it eventually started working.

Interestingly, once it started working, subsequent attempts to close and reopen the project resulted in a very fast startup.

Later, after putting my computer to sleep and waking it up (WSL was left running), the startup time became slow again — it took several minutes just like the first time.

14

When the link is lost, is there a large amount of disk io? It is known that the wsl memory setting is insufficient. Setting swap and mapping through network disk instead of using virofs for mapping will occupy a large amount of io and cause blocking during compilation and other operations. It is recommended to set a larger memory, turn off swap, turn on CPU virtualization, limit memory usage in the windows configuration file .wslconfig, and turn on kernel virtualization-level disk mapping virofs instead of using the default smb for file access operations.

16

Thanks for the helpful advice!!

I’m considering the following settings in my .wslconfig:

[wsl2]
memory=16GB  
swap=0
localhostForwarding=true

When I check memory allocation using free -h, I get the following result, so it might not be necessary to explicitly set memory:

              total        used        free      shared  buff/cache   available
Mem:           15Gi       1.8Gi        12Gi       3.0Mi        1.0Gi        13Gi
Swap:         4.0Gi          0B        4.0Gi

Also, when I run mount | grep /mnt, I get the following output, which seems to indicate that virofs is not being used:

C:\ on /mnt/c type 9p

How can I enable virofs instead of 9p for /mnt/c?